The Coventry Blue Coat Choir, which play St.Cuthbert's in the film, spent time standing in a swimming pool in order to hone their breathing techniques prior to singing.
The competition scenes were filmed in the Courtyard Theatre in Stratford-upon-Avon, the same theatre where David Tennant played his famous Hamlet (2009).
In the movie David Tennant plays twin brothers Donald & Roderick Peterson, but in the credits it lists Mr Tennant as playing David & Roderick Peterson.